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Asymmetric Organocatalysis. From Biomimetic Concepts to Applications in Asymmetric Synthesis. By Albrecht Berkessel and Harald Grger

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Angewandte
Books
Chemie
Asymmetric Organocatalysis
From Biomimetic
Concepts to Applications in Asymmetric Synthesis.
By Albrecht Berkessel and Harald
Grger. Wiley-VCH,
Weinheim 2005.
440 pp., hardcover
E 149.00.?ISBN
3-527-30517-3
This first major text on ?organocatalysis? serves the timely purpose of cataloging the rapidly growing family of enantioselective transformations catalyzed
by small organic molecules. Here, a
strategy for asymmetric catalysis that
began to permeate the synthetic organic
chemistry literature nearly a century
ago, but which has recently undergone
explosive growth, is unified and
thoughtfully compiled. The volume is
organized according to reaction types,
and delivers a nearly exhaustive account
of the field, ranging from the studies on
the cinchona-alkaloid-catalyzed asymmetric hydrocyanation of benzaldehyde
by Bredig and Fiske in 1912 up to methods published in early-to-middle 2004.
Thus, the reader is afforded access to
an easily navigated and up-to-date
arsenal of organocatalytic methods that
can be applied to an astonishingly
diverse range of synthetic problems.
In Chapters 1 and 2, a fascinating
historical overview of the field of organocatalysis is provided, along with general mechanistic considerations. Milestones in the evolution of organocatalysis are presented, beginning with its origins in enzyme-inspired biomimetic
chemistry. Here, it is interesting to note
Angew. Chem. Int. Ed. 2005, 44, 4285 ? 4287
that while ?critical mass? has been achieved only recently, key experimental
and conceptual contributions were put
forth at very early stages. For example,
the use of amino acids as catalysts in
the aldol reaction dates back to 1931,
the very term ?organic catalyst? was
coined in 1932, and the distinction
between processes that proceed through
covalent and noncovalent adducts was
made as early as 1928. The authors
then chronicle the intermittent appearance of highly enantioselective organocatalytic transformations in the latter
half of the 20th century, and the ultimate
culmination of these works into a cohesive and multifaceted area of research
that is separate from organometallic
and enzymatic catalysis. The authorsattention to historical detail pervades
all subsequent chapters, greatly enriching the text by providing yet another
layer of organization.
Chapter 3 deals with nucleophilic
substitution at aliphatic carbon atoms.
Seminal contributions by researchers
from Merck on the asymmetric alkylation of indanones reveal the utility of
alkaloid-based chiral phase-transfer catalysts. This innovation spawned an even
larger body of work pertaining to the
alkylation of benzophenone imines of
glycine. Orthogonal organocatalytic
approaches to this problem are represented by enamine catalysis and nucleophilic (Lewis base) catalysis. These
latter two strategies figure prominently
in approaches to asymmetric carbon?
halogen bond formation.
In Chapters 4?7, transformations
involving nucleophilic addition to polarized p bonds are described. Chapter 4
deals primarily with the asymmetric
conjugate addition of various carbon
and heteroatom nucleophiles to
enones. The strategies employed are surprisingly diverse, and involve the use of
chiral bases and chiral phase-transfer
catalysts, as well as activation of nucleophilic and electrophilic partners by
enamine and iminium-ion catalysis,
respectively. Nucleophilic cyclopropanation of enoates is also described.
Chapters 5 and 6 deal with nucleophilic
addition to C=N and C=O p bonds,
respectively. The majority of the discussion in Chapter 5 is devoted to Mannich
additions and imine hydrocyanation
(the Strecker reaction). The aziridinawww.angewandte.org
tion and hydrophosphonylation of
imines is also described. Chapter 6 on
carbonyl addition encompasses a broad
range of topics: carbonyl hydrocyanation and hydrophosphonylation, aldol
addition, the Morita?Baylis?Hilman
reaction, and the allylation, alkylation,
and epoxidation of carbonyl compounds. Acyl anion chemistry, as represented by the benzoin and Stetter reactions, is also described. Finally, in Chapter 7, a review of the application of azodicarboxylates and nitroso compounds
to the a-amination and a-oxygenation
of carbonyl compounds demonstrates
the effectiveness of organocatalytic
approaches to N=N and N=O p-bond
additions.
The remaining chapters, 8?14, cover
an equally diverse and exciting set of
topics. Chapter 8 highlights the application of organocatalysis to Diels?Alder
and [3� cycloadditions. Here, iminium
ion catalysis, which involves activation
through covalent catalyst?substrate
adducts, and hydrogen-bonding catalysis, which involves substrate activation
through noncovalent catalyst?substrate
association, are both revealed to be
powerful strategies. Enantioselective
phosphine-catalyzed [3� cycloaddition is also described. The enantioselective protonation/tautomerization of
enol derivatives is presented in Chapter 9. Here, it is noteworthy that while
most stereogenic centers embody a
hydrogen substituent, the photochemically induced deconjugation of enones
in the presence of chiral amino alcohols
remains the most effective method for
enantioselective protonation/tautomerization, suggesting significant opportunities for development.
Chapters 10 and 11 deal with the
topics of oxidation and reduction,
respectively. A survey of the myriad catalysts that can be used for alkene epoxidation via dioxirane and oxaziridinium
intermediates underscores one of the
main advantages of organocatalysis:
the prospect of nearly infinite structural
variation of catalysts that are readily
characterized. In addition to the epoxidation of electron-rich and electrondeficient alkenes, an account of asymmetric sulfoxidation and the oxidative
kinetic resolution of alcohols is provided. Chapter 11 deals exclusively
with carbonyl reduction. In addition to
) 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4285
Books
oxazoborolidine-catalyzed ketone reduction, chiral phase-transfer catalysis and
chiral Lewis base activation of silanes
are described.
Nucleophilic catalysis also plays a
central role in Chapters 12 and 13. In
Chapter 12, enantioselective acyl transfer is applied to the kinetic resolution
of alcohols and amines. Nitroxyl radical
catalyzed oxidative kinetic resolution is
also highlighted as an emergent and
mechanistically orthogonal approach.
Chapter 13 deals with the desymmetrization and kinetic resolution of anhydrides, meso-epoxides, and related prochiral substrates. In the case of the anhydride chemistry, both phosphorus- and
nitrogen-centered acyl transfer catalysts
are used to good advantage. For the
organocatalytic desymmetrization of
epoxides, substoichiometric quantities
of a chiral diamine are used in conjunction with a terminal basic reagent to provide enantiomerically enriched allylic
alcohols.
This monograph concludes with a
chapter entitled ?Large-Scale Applications of Organocatalysis?. Four case
studies are presented: the Julia-Colonna
epoxidation, the Strecker reaction, the
alkylation of cyclic ketones and glycinates, and the Hajos?Parrish?Eder?
Weichert?Sauer reaction. Given the
explosive growth in this burgeoning
area of research, an entirely separate
treatise on industrial applications of
organocatalysis will likely be merited
in the near future! Finally, an appendix
is provided in which catalysts appearing
throughout the text are catalogued by
structural type.
In Asymmetric Organocatalysis, Berkessel and GrEger deliver an authoritative and well-organized account of the
amazingly broad range of enantioselective transformations catalyzed by small
organic molecules. This fascinating
monograph captures the diversity and
power of an area of research whose
roots extend deep within the organic
chemistry literature, yet which has only
recently achieved critical mass through
the collective contributions of many
present-day pioneers. As the first
major text of its kind, Asymmetric Organocatalysis is an essential addition to
both academic and industrial research
libraries, as well as to the personal col-
4286
lection of any scientist with an interest
in catalysis or synthetic chemistry.
Michael J. Krische
Department of Chemistry and
Biochemistry
University of Texas
Austin, Texas (USA)
DOI: 10.1002/anie.200585291
Analytical Chemistry
A Modern
Approach to Analytical Science, 2nd
Edition. Edited by
Robert Kellner, JeanMichel Mermet,
Matthias Otto,
Miguel Valc$rel and
H. Michael Widmer.
Wiley-VCH, Weinheim 2005.
1181 pp., hardcover
E 79.00.?ISBN
3-527-30590-4
This textbook is intended to provide a
comprehensive overview of modern
analytical chemistry. From a first
glance through the list of contents,
which shows that there are eight main
sections containing 36 chapters altogether, plus an appendix and subject
index, it is clear that the editors have
set out to provide a work that covers
the entire broad field of analytical
chemistry. It deals with every aspect,
ranging from the fundamental principles
of the analytical process, through elemental analysis and surface analysis, to
sensors and automated analytical systems. That has been achieved by a
team of 29 authors whose names,
which include many illustrious ones,
are a guarantee of competence in their
specialist fields. However, such multiple
authorship carries the risk of some nonuniformity with regard to structure,
style, and level of treatment, and the
editors have not managed to avoid that
completely.
) 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
The first six chapters give the reader
a detailed introduction to analytical
chemistry as a chemical (and biochemical) discipline. Important concepts and
terms are explained thoroughly and are
well illustrated. Possible problems and
potential sources of error, which the
analytical chemist must always keep in
mind and guard against, are also discussed in detail. This didactic approach
is continued in Chapter 7, which is
devoted to the important matter of quality assurance and control, and in Chapter 8 on chemometric methods in analytical chemistry. Some important fundamental principles that are essential for
an understanding of analytical methods
are covered in Chapters 9?17. The very
effective didactic treatment is especially
evident in the clear and informative
examples of working practice, and in
the exercise questions at the ends of
the chapters. However, students would
have benefited from being given more
complete answers to the questions.
Chapters 18?26 are concerned with
three topic areas: electroanalytical
methods, separation methods, and
atomic and molecular spectroscopy. In
principle, all the commonly used
modern techniques are described, but
the relative emphasis given to the different topics does not always reflect their
true importance and the latest state of
the art. An example of this is seen in
the treatment of inductively coupled
plasma mass spectrometry (ICP-MS),
which is now the most important routinely used method for elemental trace
and ultratrace analysis. It receives
rather thin coverage, especially when
compared with techniques such as
field-flow fractionation, which is given
more space, and thus greater attention.
Unfortunately, there are other unsatisfactory examples where the newcomer
to analysis is not presented with a true
picture of the relative importance of different topic areas.
A definite advantage of this textbook compared with other works of
the kind is seen in Chapters 27 and 28,
which deal with surface analysis. This
very important area of analytical
chemistry is presented clearly, covering
all the main state-of-the-art methods. It
is interesting that microscopy techniques (which are often neglected in analytical chemistry textbooks) are
Angew. Chem. Int. Ed. 2005, 44, 4285 ? 4287
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